| 1Cr13 martensitic stainless steel belongs to high hardenability steel. By quenching and high temperature tempering, it can get high strength and high toughness, so that widely used at home and abroad. However, if after the improper heat treatment,the material is easy to produce ferrite, which has serious impact on the impact toughness, especially the low temperature impact toughness. Therefore, it has important theoretical significance and practical value to research on microstructure evolution law of 1Cr13 martensitic stainless steel during heat treatment, and reveal the factors affecting the impact toughness at low temperature. In this paper, using Jmat-Pro software to simulate and analysis the influence of chemical composition and quenching temperature on ferrite precipitation of 1Cr13 martensitic stainless steel,which is the research object; Quenching with different process parameters on the basis of results all above for the experimental materials, and with the use of optical microscopy(OM) observation to analyze the sample of as-forged, or though high temperature quenching, high temperature tempering, annealing and to reveal influence of the quenching process parameters on ferrite precipitation law; At the same time, stretching at room temperature and impact properties at low temperature was carried out, which revealed the relationship between the quenching process parameters, quantity of ferrite and mechanical properties. The main conclusions are as follows:1. Through the Jmat-Pro software simulation, the ferrite quantity decrease with the increase of Ni,C and Mn content, while the quantity increases with the increase of Cr and Si content; When the 1Cr13 martensitic stainless steel components is certain conditions(C0.094%, Mn0.42%, Si0.4%, Cr13.35%, Ni0.35%), the ferrite decreases from 98.19% to 0.3% when quenching temperature increases from 810? to 970?in the process. The ferrite increases from 0.3% to 100% when quenching temperature increases from 970? to 1360? in the process,and ferrite precipitation content is least which quenching at 970?; On the basis of the above computer simulation, the quenching experiment of as-forged 1Cr13 martensitic stainless steel is put into practice. Though the observation of the microstructure, the results are almost consistent with the evolution of the computer simulation.2. The different samples of as-cast 1Cr13 martensitic stainless steel were obtained by high temperature quenching, high temperature tempering and annealing treatment. And then the quenching treatment under the same quenching process parameters was carried out. The results show that: the change of quenching temperature influence the evolution of ferrite by the original microstructure. Whether after the high temperature quenching, high temperature tempering or annealing, the evolution of the ferrite are basically the same as computer simulation and the cast microstructure test results when requenching from 800? to 1250?. However, the ferrite quantity has a certain relationship with the original microstructure though the same quenching temperature process.Namely,the ferrite precipitation of test sample after high temperature tempering is least; after high-temperature quenching, the ferrite precipitation of the sample was most. While, if the samples were annealed,the amount of the precipitation ferrite is consistent with the as-cast microstructure.3. By ?1 990?normalizing + quenching at different temperature +high temperature tempering and ?2 annealing + 990?normalizing + quenching at different temperature + high temperature tempering for 1Cr13 martensitic stainless steel coarsed sample, the effects on ferrite precipitation behavior and mechanical properties of different pretreatment microstructure after different quenching and tempering were comparative analysed. The results show that: After 990?normalizing + different temperature quenching, the ferrite content decreased from 25% to 5% at the range from 850? to 950?, and the ferrite content increased from 5% to 45% between 950? to 1250?. After annealing process, the samples were normalized in order. Then though quenching at different temperature, the ferrite evolution was similar with it, and did not change significantly. Though ?1 ?2 heat treatment and comparative analysis, it is concluded that the ferrite decreases firstly and then increases. And the effect of annealing process on the grain size and distribution of ferrite had a little influence; The mechanical test results means that the section shrinkage and elongation decreased with the increasing quenching heating temperature, and the tensile strength increased with increasing quenching temperature. The low-temperature impact work of specimen reached the maximum in 950?. And the mechanical properties of samples after ?2 heat treatment is higher than the samples of after ?1 heat treatment except tensile strength. In summary, the best heat treatment process for 1Cr13 martensitic stainless steel is 880?annealing + 990?normalizing + 950?quenching + 750?tempering. |
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